The Obama administration is now urging some criminals in U.S. prisons to plead for clemency. Many of these prisoners were sentenced under tough drug laws from the days of the crack epidemic. And now, the Justice Department says that low level, non-violent drug offenders should ask for early release. The U.S. Senate Judiciary Committee, meanwhile, is pushing a bill that advocates are calling the biggest sentencing reform in decades.

CARRIE JOHNSON, BYLINE: The biggest single catalyst, Rachel, is the budget. Justice Department officials say that the prison budget, the budget for about 119, 120,000 federal inmates, threatens to eat up one-third of the entire funding for the Justice Department. And that means less money to hire FBI agents and DEA agents, less money to help local police, and less money to prosecute cases. So in some ways it's a security threat.

The Obama administration in particular has been highlighting the fact it's also a civil rights issue, because so many of these charges disproportionately impact people of color - particularly African-American men and Latino men, as opposed to white defendants. And finally, Rachel, there is a path forward from the states; there's a template from the states. Many red states, like Texas and South Carolina and Georgia have already made these kinds of reforms. And conservatives there are on board.

MARTIN: So, Carrie, how would these proposals on the table, how would they work and what would be the implications?

JOHNSON: For starters, on clemency - the issue that the deputy attorney general recently brought up - bringing more cases to the Justice Department attention. Cases of inmates who are already behind bars would give the White House a bigger pool from which to choose inmates who could be sent home earlier or sent home right away. Their sentences could be commuted and the like. This essentially would involve people who are nonviolent offenders, who have been put behind bars for a long, long time due to drugs

And then, in Congress, the separate set of proposals that out there would cut in half a whole bunch of mandatory minimum sentences for drug crimes. The sentencing proposals in the Senate would also allow about 8,000 or 9,000 inmates who are currently in prison, under those tough old drug laws, to seek retroactive help and get them out earlier.

Now, the Senate proposal is interesting because it involves an unusual political coalition. Not just old-time Democrats like Richard Durbin of Illinois and Patrick Leahy of Vermont, but also some Tea Party favorites like Mike Lee of Utah and Ted Cruz of Texas.

MARTIN: So there is some strong opposition to changing some of these laws, too, though I imagine.

JOHNSON: For sure. And the opposition is coming loudest from a group called the National Association of U.S. Attorneys. This group sent a letter to Senate and said that the power to make charging decisions in drug cases should rest with prosecutors, not lawmakers. These prosecutors say they don't bring penny ante cases, dime bag cases in federal system. And these mandatory minimums, already on the books, give prosecutors a lot of leverage to build cases and get cooperation from low-level offenders.